Study links 77% obesity risk in teens to parents' BMI at same age

New Delhi: One's Body Mass Index (BMI) could be explained genetically, researchers have said after they found a 77 per cent chance of children developing obesity at the age of 17 if their parents had the condition at the same age.

A team of researchers, including those at Tel Aviv University, used data of more than 13 lakh people recorded between 1986 and 2018 during screening before their compulsory military service in Israel.

BMIs of children aged 17 were compared with those of both their parents when they were the same age. Data was available for 24 per cent of over 4.45 lakh trios included in the analysis.

"Among trios in which both parents had a healthy BMI, the prevalence of (being) overweight or obesity in the offspring was 15.4 per cent, this proportion increased to 76.6 per cent when both parents had obesity," the authors wrote in the study published in The Journal of the American Medical Association (JAMA) Network Open.

The researchers also found a correlation between the average of the father's and mother's BMI with that of their child and estimated that BMI was 39 per cent heritable. The correlation between father-son BMI was found to be 0.273, indicating that a son's BMI could be influenced by the father's by up to 27 per cent.

Further, the authors found a stronger correlation between BMIs of mothers and daughters, compared with those of mothers and sons. Mothers with obesity have been previously linked with higher chances of daughters developing the condition, compared with fathers having obesity.

The result, therefore, underscores gender-specific influences on the heritability of BMI, along with genetic and environmental factors, the authors said.